The compound N-{4-(2,2-dimethyl-propionyl)-5-[(2-ethylamino-ethanesulfonylamino)-methyl]5-phenyl-4,5-dihydro-[1,3,4]thiadiazol-2-yl}-2,2-dimethyl-propionamide was first described in PCT International Publication Number WO 03/051854. A formulation containing the compound N-{4-(2,2-dimethyl-propionyl)-5-[(2-ethylamino-ethanesulfonylamino)-methyl]-5-phenyl-4,5-dihydro-[1,3,4]thiadiazol-2-yl}-2,2-dimethyl-propionamide is described in PCT international Publication Number WO 2004/092147. A formulation containing the compound N-{4-(2,2-dimethyl-propionyl)-(5R)-5-[(2-ethylamino-ethanesulfonylamino)-methyl]-5-phenyl-4,5-dihydro-[1,3,4]thiadiazol-2-yl}-2,2-dimethyl-propionamide is described in PCT International Publication Number WO 2006/101102. This compound is useful, for example, for therapeutic treatment of a human malignant tumor.
Stable formulations of the compound N-{4-(2,2-dimethyl-propionyl)-(5R)-5-[(2-ethylamino-ethanesulfonylamino)-methyl]-5-phenyl-4,5-dihydro-[1,3,4]thiadiazol-2-yl}-2,2-dimethyl-propionamide which minimize chiral conversion to the less active S enantiomeric form are desired for reproducible and efficient manufacturing and commercial scale preparation, long-term storage of a lyophilized form, and stability when the lyophilized form is reconstituted and delivered to a patient. Surprisingly, formulation parameters and manufacturing conditions were discovered that provide stable pharmaceutical compositions comprising N-{4-(2,2-dimethyl-propionyl)-(5R)-5-[(2-ethylamino-ethanesulfonylamino)-methyl]-5-phenyl-4,5-dihydro-[1,3,4]thiadiazol-2-yl}-2,2-dimethyl-propionamide that minimize undesirable chiral conversion to the less active S enantiomeric form.